Triple-negative breast cancers are a heterogeneous group of tumors that are, as yet, not entirely understood. Although triple-negative carcinomas are strictly defined as invasive carcinomas lacking expression of estrogen receptor, progesterone receptor, and HER2, some use the terms triple-negative and basal-like cancer synonymously. It should be noted that these are not entirely equivalent. Nevertheless, it has been shown that a panel of immunohistochemical markers can be used as a surrogate for genomic profiling and thus to identify basal-like breast cancers. We describe the panels of immunohistochemical markers that can be applied and how to interpret these markers herein.
Keywords: Basal-like breast carcinoma; ER; HER2; Immunohistochemistry; Triple-negative breast cancer.